1. Field of the Invention
The present invention relates to an organic electroluminescent display, and more particularly, to a method of fabricating an organic electroluminescent display (hereinafter abbreviated OELD) enabling to increase a throughput efficiency by carrying out a foregoing OELD process, dividing a large-scaled substrate, and carrying out a following OELD process in order.
2. Background of the Related Art
As information telecommunication technologies have been greatly developed, demands for electronic display devices are highly increased to keep up with the developing information society. And, so does the demands for various displays. In order to satisfy the demands of the information society, for electronic display devices are required characteristics such as high-resolution, large-size, low-cost, high-performance, slim-dimension, and small-size and the like, for which new flat panel displays (hereinafter abbreviated FPD) are developed as substitutions for the conventional cathode ray tube (CRT).
The FPDs include LCD (liquid crystal display), ELD (electroluminescent display), PDP (plasma display panel), FED (field emission display), VFD (vacuum fluorescence display), and LED (light emitting display), and the like.
Compared to the non-emissive device such as LCD, ELD attracts attention as the next generation FPD because ELD has a response speed faster than that of the non-emissive display, excellent brightness by self-luminescence, easy fabrication thanks to a simple structure, and light-weight/slim design. Thus, ELD is widely applied to various fields such as LCD backlight, mobile terminal, car navigation system (CNS), notebook computer, wall TV, and the like.
Such an ELD is divided into two categories, i.e. organic electroluminescent display (hereinafter abbreviated OELD) and inorganic electroluminescent display (hereinafter abbreviated IELD) in accordance with materials used for luminescent layers respectively.
IELD, which emits light using the collisions of electrons accelerated by an high electric filed, is classified into AC thin film ELD, AC thick film ELD, DC thick film ELD, and the like in accordance with thickness of the thin films and driving systems.
And, OELD, which emits light by a current flow, is classified into low-molecular OELD and high-molecular OELD.
FIG. 4 illustrates a schematic cross-sectional view of OELD according to a related art.
Referring to FIG. 4, stacked on a transparent substrate 11 in order are a transparent anode layer 12, a hole injection layer 13, a hole transport layer 14, an organic luminescent layer 15, an electron transport layer 17, and a cathode layer 18 made of metal. And, the organic luminescent layer 15 emits light by a current flow. The hole injection, hole transport, and electron transport layers 13, 14, and 17 play a subsidiary role in increasing a luminescence efficiency of OELD.
The hole injection, hole transport, organic luminescent, and electron transport layers 13, 14, 15, and 17 are formed by vacuum deposition using a shadow mask if formed of a low molecular material. And, the hole transport, and organic luminescent layers 14, and 15 are formed by ink-jet or printing if formed of a high molecular material. The limitation of the deposition or printing equipment restricts the size of a substrate. The maximum size of the substrate enabling to use the current deposition or printing equipment for the deposition or printing is 370 mmxc3x97470 mm or 400 mmxc3x97400 mm.
OELD is classified into the following devices in accordance with the luminescent (light-emitting) materials. First, there is a fluorescent display disclosed in U.S. Pat. Nos. 4,769,292 and 5,294,870, in which the organic luminescent layer 15 is formed of a fluorescent emitting material such as aluminum tris(8-hydroxyquinoline) (Alq3), perylene or the like. Second, there is phosphorescent OELD disclosed in U.S. Pat. No. 6,097,147, in which the organic luminescent layer 15 is formed of one of phosphorescent emitting materials such as platinum 2,3,7,8,12,12,17,18-octaethyl-21H,23H-porphine platinum (PtOEP), iridium complex {ex. Ir (Ppy) 3} and a blocking layer is formed between the hole and electron transport layers 14 and 17 using one of bathocuproine (BCP), cabazole biphenyl (CBP), N,Nxe2x80x2-diphenyl-N,Nxe2x80x2-bis-alpha-napthylbenzylidine (NPD), and the like. Specifically, high molecular OELD has a double-layered structure including hole transport/electroluminescent layers 14/15 between the transparent anode and cathode layers 12 and 18, for which conductive high molecules of conjugated polymer disclosed in U.S. Pat. No. 5,399,502 and U.S. Pat. No. 5,807,627 are used. The conductive polymer includes {poly(p-phenylenevinylene), PPV}, poly(thiophene), {poly(2,5-dialkoxyphenylenevinylene, PDMeOPV)}, and the like.
Luminescent wavelengths of the representative organic electroluminescent materials are shown in Table 1.
Such OELD is classified into active and passive types according to its driving system. If the panel size of the passive type OELD driven by current increases, an efficiency of power consumption as well as device reliance decreases. In order to settle such problems, if a diagonal diameter of a panel is at least 10xe2x80x3, the active type OELD using polysilicon thin film transistors (hereinafter abbreviated TFT) is used.
Unfortunately, OELD according to the related art has the following problems or disadvantages.
The electroluminescent layer of OELD is formed by deposition using a shadow mask or printing. Thus, the limitation of equipments of deposition or printing restricts the size of the substrate. The available size of the substrate is maximum 370 mmxc3x97470 mm or 400 mmxc3x97400 mm.
Therefore, such a restriction of the substrate size also restricts productivity (throughput) of OELD so as to increase a product cost.
Accordingly, the present invention is directed to a method of fabricating an organic electroluminescent display that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a method of fabricating an organic electroluminescent display (hereinafter abbreviated OELD) enabling to increase a throughput efficiency by carrying out a foregoing OELD process, dividing a large-scaled substrate, and carrying out a following OELD process in order.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages, and in accordance with the purpose of the present invention as embodied and broadly described, a method of fabricating an organic electroluminescent display includes the steps of forming a first electrode layer on a large-scaled substrate, dividing the large-scaled substrate into a plurality of small substrates, forming an organic electroluminescent layer on the first electrode layer of at least one of the small substrates, and forming a second electrode layer on the organic electroluminescent layer.
In another aspect of the present invention, a method of fabricating an organic electroluminescent display includes the steps of forming a driving part including a plurality of transistors and at least one capacitor and having a first electrode layer on a large-scaled substrate, dividing the large-scaled substrate into a plurality of small substrates, forming an organic electroluminescent layer on the first electrode layer of the driving part of at least one of the small substrates, and forming a second electrode layer on the organic electroluminescent layer.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.